Method for producing homogeneous fine grain titanium materials suitable for ultrasonic inspection

ABSTRACT

A titanium material production method for producing homogeneous fine grain titanium material in which the titanium material has a grain size in a range from about 5 μm to about 20 μm. The method comprises providing a titanium material blank; conducting a first heat treatment on the titanium material blank to heat the titanium material blank to a β-range; quenching the titanium material blank from the β-region to the α+β-region; forging the titanium material blank; and conducting a second heat treatment on the titanium material blank. The titanium material production method subjects the titanium material blank to superplasticity conditions during part of the titanium material production method.

BACKGROUND OF THE INVENTION

The invention relates to titanium material production methods. Inparticular, the invention relates to titanium material productionmethods that can produce titanium materials suitable for inspectionusing ultrasonic energy inspection methods and systems.

The production of titanium material with titanium material grain sizesand nature of αTi particle colony structures may be important variablesthat influence titanium material applications. Further, size of titaniumgrains and a nature of αTi particle colony structures may influence theultrasonic noise and ultrasonic inspection in single phase and two-phasetitanium alloys and materials, in which the ultrasonic inspection can beused to determine suitability of the titanium material for variousapplications. The size of titanium grains and the nature of αTi particlecolony structures may influence ultrasonic inspection techniques,methods, and results by creating undesirable noise during ultrasonicinspection. This noise may hide or mask critical flaws in titanium thatmay limit applications of the titanium.

Colony structures are formed during titanium material productionmethods, for example during cooling a titanium material from a hightemperature. The colonies are believed to form as βTi transforms to αTiand may define a “textured” titanium material microstructure. Acrystallographic relation exists between the αTi and the parent βTigrain, such that there are only three crystallographic orientations thatαTi will take forming from a given βTi grain. If the cooling rate ishigh and there is uniform nucleation of αTi throughout the grain,neighboring αTi particles have different orientations, and each behaveas a distinct acoustic scattering entity. However, if there are only afew sites of αTi nucleation within the βTi grain, then the αTi particlesin a given area all grow with the same orientation, and a colonystructure results. This colony becomes the acoustic entity. Since acolony is formed within a βTi grain, the colony size will be less thanthe βTi grain size. While thermomechanical processing techniques thatrely on dynamic recrystallization in the α+β temperature range toachieve uniform fine grain (UFG) αTi particles and prevent colonyformation have been developed to improve titanium microstructure,defects may remain in the titanium material. These defects may beundesirable for some titanium material applications. Thus, the defectsshould be discovered prior to use of the titanium material in variousmicrostructurally sensitive applications.

Titanium material production methods are known and are varied. One suchtitanium material production method relies on dynamic recrystallizationof titanium material in the α+β temperature range. Thisrecrystallization is intended to achieve relatively uniform fine grain(UFG) αTi particles and prevent colony formation. While this type ofrecrystallization has been proposed to improve titanium materialmicrostructure, defects may remain in the titanium material, and thesedefects may limit applications of the titanium material. Some of thedefects in the titanium material may be difficult to detect usingconventional ultrasonic inspection techniques and methods.

Nondestructive evaluation of articles and structures by ultrasonicinspection and ultrasonic inspection is a known testing and evaluationmethod. Ultrasonic inspection and testing typically requires thatdefects or flaws in the articles and structures possess differentacoustic behaviors from bulk material articles and structures undergoingsimilar ultrasonic inspection to be detectable. This different behaviorpermits the ultrasonic inspection to detect flaws, grains,imperfections, and other related microstructural characteristics(defects) for a material. Materials forming articles and structures withlarge, elastically anisotropic grains, such as, but not limited to, castingots of steels, titanium alloys, and nickel alloys, are oftendifficult to evaluate by ultrasonic testing. The difficulties arise, atleast in part to, because sound waves, which are used for ultrasonicinspection, are reflected from grains and grain arrays sharing commonelastic behavior, and represent a background “noise.” The generatedbackground noise can mask flaws in the material, and is thusundesirable.

Ultrasonic inspection techniques have been developed that use focusedultrasonic beams to enhance a flaw fraction within any instantaneouslyinsonified volume of material in articles and structures. Thesedeveloped ultrasonic inspection techniques can identify indicationsbased both on maximum signal, as well as signal to noise. A scatteringof sound in a polycrystalline metallic material body, which is alsoknown in the art as an attenuation of a propagating sound wave, can bedescribed as a function of at least one of grain dimensions, intrinsicmaterial characteristics, and ultrasound frequency. Typically, threedifferent functional relationships among scattering, frequency, andgrain dimensions have been described. These are:

-   for λ>2πD, a equal to about Tv⁴Θ, termed “Rayleigh” scattering;-   for λ<2πD or λ≅D, α equal to about Dv²Σ, termed “stochastic” or    “phase” scattering; and-   for λ<<D, a ∝1/D, termed “diffusion” scattering;-   where a is attenuation, λ is wavelength of the ultrasound energy, v    is frequency of the ultrasound energy, D is an average grain    diameter, T is a scattering volume of grains, and Θ and Σ are    scattering factors based on elastic properties of the material being    inspected.

A titanium material microstructure can be determined by measuring thescattering of sound in a material. A titanium material microstructure'ssound scattering sensitivity can be attributed to αTi particles that arearranged into colonies. These titanium material colonies typically havea common crystallographic (and elastic) orientation, and these coloniesof αTi particles can behave as large grains in the titanium material.

An individual αTi particle might be about 5 μm in diameter, however, acolony of αTi particles could be greater than about 200 μm in diameter.Thus, the size contribution attributed to sound scattering sensitivityfrom αTi particles could vary, for example vary over 40-fold, amongdiffering microstructures. Additionally, the sound scatteringsensitivity due to αTi particles could change between that from randomlycrystallographically oriented αTi particles to that from αTi particleswithin crystallographically oriented colonies of αTi particles.

While ultrasonic inspection of most titanium material articles can bepreformed with some degree of certainty, the shape, size, configuration,structure, and orientation of the articles, titanium material grains andmicrostructures formed during a titanium material production methodundergoing ultrasonic inspection may impair the ultrasonic inspection.Thus, in order to have acceptable titanium material for certainapplications, it is desirable to provide titanium material productionmethods that produce titanium articles and structures that can besubjected to an ultrasonic inspection that enhances the determinationand differentiation of noise during ultrasonic inspection. Thus, theultrasonic inspection method can determine if ultrasonic inspectionnoise is attributed to a defect in the titanium material, or is due toother factors.

Therefore, a need exists for a titanium material production method thatis suitable for producing titanium material, articles, and structuresfor ultrasonic inspection methods that can be subjected to an ultrasonicinspection that enhances the determination and differentiation of noiseduring ultrasonic inspection.

SUMMARY OF THE INVENTION

A titanium material production method for producing homogeneous finegrain titanium material in which the titanium material has a grain sizein a range from about 5 μm to about 20 μm is provided by the invention.The method comprises providing a titanium material blank; conducting afirst heat treatment on the titanium material blank to heat the titaniummaterial blank to a β-range; quenching the titanium material blank fromthe β-region to the α+β-region; forging the titanium material blank; andconducting a second treatment on the titanium material blank. Thetitanium material production method subjects the titanium material blankto superplasticity conditions during the titanium material productionmethod.

A titanium material production method for producing homogeneous finegrain titanium material in which the titanium material has a grain sizein a range from about 15 μm to about 20 μm, generally equiaxed titaniumgrains and generally equally sized titanium grains, and substantiallyeven distribution of second phase particles and alloying elements isalso provided by the invention. The method comprises steps of: providinga titanium material blank, the titanium material comprising a two-phasetitanium material; conducting a first heat treatment on the titaniummaterial blank to heat the titanium material blank to a β-range;quenching the titanium material blank from the β-region to theα+β-region; forging the titanium material blank; and conducting a secondheat treatment on the titanium material blank. The titanium materialproduction method subjects the titanium material blank tosuperplasticity conditions during the titanium material productionmethod. The titanium material production method comprises heating thetitanium material blank to a temperature in a range from about 600° C.to about Tpt, wherein Tpt is a These and other aspects, advantages andsalient features of the invention will become apparent from thefollowing detailed description, which, when taken in conjunction withthe annexed drawings, where like parts are designated by like referencecharacters throughout the drawings, disclose embodiments of theinvention.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 illustrates light micrographs of Ti6242 material that in thefollowing conditions: (a) conventional billet; (b) conventional forging;(c) uniform fine grain (UFG) billet; (d) a forging of a UFG billet;

FIG. 2 illustrates icosahedral images generated from EBSP analysis of aTi6242 material in the following conditions: (a) conventional billet;(b) conventional forging; (c) UFG billet; (d) forged UFG billet;

FIG. 3 illustrate [0001] pole figures generated from EBSP analysis of aTi6242 material in the following conditions: (a) conventional billet;(b) conventional forging; (c) UFG billet; (d) forged UFG billet;

FIG. 4 illustrate 5 MHz C-scan images of Ti6242 blocks containing arraysof 0.79 mm ({fraction (1/32)} inch) diameter flat bottom holes, whichare drilled 25 mm below a surface, in which the top left is titanium UFGbillet, the top right is a conventional titanium billet, the bottom leftis a conventional titanium forging, and the bottom right is a titaniumUFG forging, whereing the 5 MHz C-scan images are taken at 12 dBattenuation noise scan;

FIG. 5 illustrate 5 MHz C-scan images of Ti6242 blocks containing arraysof 0.79 mm ({fraction (1/32)} inch) diameter flat bottom holes, whichare drilled 25 mm below a surface, in which the top left is titanium UFGbillet, the top right is a conventional titanium billet, the bottom leftis a conventional titanium forging, and the bottom right is a titaniumUFG forging, wherein the 5 MHz C-scan images are taken at 34 dBattenuation signal scan;

FIG. 6 illustrates a graph of average signals from flat bottom holeswith respect to those in the block machined from the conventionalbillet;

FIG. 7 illustrates a graph of average noise from blocks referenced tothat from the block machined from the conventional billet; and

FIG. 8 illustrates a graph of signal to noise ratios of Ti6242 blocks asa function of frequency.

DESCRIPTION OF THE INVENTION

A titanium material production method, as embodied by the invention,comprises a plurality of metallurgical processing steps to provide atitanium material with a homogeneous, fine grain microstructure. Theproduced titanium material is suitable for various microstructurallysensitive applications, including but not limited to, turbine componentapplications. The produced titanium material can also be readilyinspected by ultrasonic inspection methods and systems. The ultrasonicinspection of the titanium material that is prodiced by a titaniummaterial production method, as embodied by the invention, will readilyindicate titanium material characteristics, for example, but not limitedto, scattering types, grain size, and other microstructurecharacteristics.

A titanium material production method, as embodied by the invention,comprises at least steps of providing a titanium material blank, inwhich the titanium material blank may be formed by suitable titaniummaterial production methods, including but not limited to, powdermetallurgy methods; heat treating the titanium material blank to atemperature in the β range for titanium; quenching of the thus heatedtitanium material blank; forging the quenched titanium material blank;and another heat treatment of the forged titanium material blank, inwhich superplasticity conditions are achieved in the titanium materialproduction method. The resultant titanium material possesses amicrostructure with a grain size in a range from about 5 μm to about 20μm, for example in a range from about 15 μm to about 20 μm.

A homogeneous fine grain titanium material microstructure is created byrecrystallization of the titanium material during the titanium materialproduction method, as embodied by the invention. The recrystallizationof the titanium material often occurs during plastic deformation of thetitanium material, for example during annealing or deformation of thetitanium material. Therefore, resultant microstructural grain size is ina range from about 5 μm to about 20 μm, for example in a range fromabout 15 μm to about 20 μm. The titanium material grain size lends to adecrease in defects in the titanium material.

Traditional titanium material plastic deformation processes are not ableto form highly homogeneous titanium material microstructures. Theseknown plastic deformation processes can result in differentmetallographic and crystallographic titanium microstructures, withdiffering inhomogeneous distributions of second phase particles anddifferent shaped particles in the titanium material microstructure. Thistitanium material microstructure, even though it may possess small grainsizes, provides considerable noise levels during ultrasonic inspection,which of course is undesirable.

A homogeneous fine grain microstructure with a grain size in a rangefrom about 5 μm to about 20 μm, for example in a range from about 15 μmto about 20 μm can be formed by the titanium material production method,as embodied by the invention. This homogeneous fine grain microstructureis formed by dynamic titanium material grain recrystallization, which isoften accompanied by a creation of second phases. Temperature and rateconditions for the titanium material production method, as embodied bythe invention, include a temperature range between about 600° C. toabout Tpt, in which Tpt is the polymorphous transformation temperaturefor the titanium material. The rate interval for the titanium materialproduction method is provided in a range from about 10⁻⁵ to about10⁻¹s⁻¹. In the titanium material production method, as embodied by theinvention, a lower deformation temperature and a higher strain rate,provides a smaller grain size. These temperature and deformation rateranges include superplastic deformation conditions, which result indynamic recrystallization of titanium material and formation ofrecrystallized titanium material grains with a size in a range fromabout 5 μm to about 20 μm.

Superplastic conditions occur under flow during one of the processingsteps of the titanium material production method, as embodied by theinvention. The titanium material microstructure can become homogeneousif the titanium material is subjected to superplastic deformation, inwhich the homogeneity provides substantially equiaxed grains withgenerally equal sized grains. Further, any titanium material secondaryphase particles can be substantially uniformly distributed in thetitanium material, and any alloying elements therein can besubstantially distributed between the phases. In general, the titaniummaterial, which is produced by a titanium material production method, asembodied by the invention, provides a generally textureless state,meaning that the titanium material does not contain colonies that wouldimpair ultrasonic inspection. As the result, the noises duringultrasonic inspection can be decreased, and the sensitivity of theultrasonic inspection enhances the detection of titanium materialdefects.

The titanium material blank that is provided by the titanium materialproduction method, as embodied by the invention, can comprise atwo-phase titanium material, for example a two-phase titanium alloy,which can be prepared by any suitable metallurgical process includingbut not limited to, powder metallurgy. The titanium alloy can compriseany suitable titanium material or titanium alloy, for example, but notlimited to, Ti64 alloys, Ti6242 alloys, Ti-5Al-2.5Sn alloys,Ti-5Al-2.5Sn-Eli alloys, IMI550 titanium alloys, VT8-1 titanium alloys,VT6 titanium alloys, and other titanium materials. The titanium alloysdiscussed herein are exemplary of the titanium materials for titaniumarticles and structures within the scope of the invention. Thedescription of titanium alloys is in no way intended to limit the scopeof the invention.

The formation of homogeneous fine grain microstructure in titaniummaterials can be related to an initial titanium material microstructurebefore any deformation. For example, an initial titanium materialmicrostructure before any deformation in the (α+β)-region tends tocomprise grains that are coarse and lamellar. This grain size is in arange from about 300 μm to about 500 μm.

A smaller and more homogeneous titanium material grain size, which canbe obtained during deformation in the β-region, can be provided duringdeformation in (α+β)-region. In order to obtain this titanium materialmicrostructure, multiple forging steps in the titanium materialproduction method are performed with a temperature around Tpt. Thus,recrystallization annealing or secondary deformation in the titaniummaterial production method is conducted in the β-region to form ahomogeneous microstructure with fine β-grains.

Dissimilar initial titanium material grain orientations, when underapplied stress in the titanium material production method, can result innon-uniform recrystallization. This non-uniform or inhomogeneousrecrystallization (textured microstructure) may lead to non-uniformdeformation distribution in the titanium material. The titanium materialproduction method, as embodied by the invention, can increasedistribution deformation homogeneity and microstructure homogeneity inthe titanium material and thus provides a desirable titanium materialmicrostructure.

The titanium material production method, as embodied by the invention,will now be discussed with reference to examples for producing titaniummaterials. These examples are merely exemplary of the titanium materialproduction methods within the scope of the invention, and are notintended to limit the invention in any manner. The scope of theinvention comprises other titanium material production methods. Further,the values, ranges, and amounts set forth in the specification areapproximate, unless otherwise indicated.

EXAMPLE 1

Titanium material blanks comprising a two-phase titanium alloy (Ti-6242)having a Tpt of about 1000° C were provided. The titanium materialblanks were cut from a deformed β-region in a titanium material rod. Thedimensions of the titanium material blanks were 100 mm by 100 mm by 200mm. The β-grain size was in from about 3 mm to about 5 mm. The titaniummaterial microstructure was extended or elongated in a direction ofdeformation.

The titanium material blanks were initially heated to a temperature inthe β-region (T equal to about 1020° C., dwelling time equal to about 1hour). The titanium material blanks were then quenched from thetemperature of the β-region to create a homogeneous fine grainmicrostructure in (α+β)-region. Disperse lamellar microstructure wasformed and a layer of α-phase titanium was formed disposed aroundboundaries of the β-grains with a reduced thickness compared toconventional titanium material production methods. This titaniummaterial production method increases grain and microstructurehomogeneity during recrystallization.

Forging in the (α+β)-region was conducted at the temperature T equal toabout 875° C. and an average strain rate of 3×10⁻³s⁻¹. An isothermalhydraulic press with the 1,600 ton capacity was used, in which the presscomprised an isothermal die block. The block was manufactured from theheat resistant nickel alloy and was heated up to the same temperature asthe blank. The deformation of the titanium material in the titaniummaterial production method was conducted by forging with changingdeformation axes. After two deformation steps (as above) were conductedone after the other, a homoheneous titanium material microstructure witha grain size of about 5 μm was formed. The strain during each forgingwas 50% with respect to a height dimension of the titanium materialblank. Sum relative strain, measured by a change in titanium materialblank area during each stage was 12. Accordingly, the titanium materialwas determined to be in superplasticity conditions because the resultantgrain size is about 5 μm, a deformation temperature was about 875° C., astrain rate ε equal to about 3×10⁻³ s⁻¹, and a rate sensitivitycoefficient m equal to about 0.39. In order to completerecrystallization of the titanium, the titanium material blanks weresubjected to annealing at the deformation temperature for a period ofabout 1 hour.

EXAMPLE 2

Titanium material blanks comprising a two-phase titanium alloy (IMI550)were provided. The alloy had a Tpt of about 965° C. for an ingot and aTpt of about 980° C. for a forging. The titanium material formed as aningot (billet) with an approximate size of 634 mm by 540 mm was preparedby a titanium material production method that included subjecting thetitanium material to a forging in the β-region. This step was followedby heat treatment at about 1200° C., and thereafter by forging androllforming. This step included settling, forging on the square, androllforming. A heat treatment step followed with heating at 1140° C. andforging to 390 mm. These steps were followed by cooling in air. Further,the titanium material production method, as embodied by the invention,included a step of heating at Tpt−30° C. and forging to 310 mm, heatingat 1060° C., forging to 280 mm, and cooling by air were conducted.Further, the titanium material blank was subjected to heating at Tpt−30°C. and forging, which included settling, forging to a square,rollforming, and forging to 245 mm. After heating the titanium materialblank in the β-region, for example Tpt+20° C., a homogeneous titaniummicrostructure with a grain size in a range from about 700 μm to about940 μm was formed. Cooling of the titanium material blanks was conductedby water quenching.

The titanium material production method, as embodied by the invention,comprised forging in the (α+β)-region for titanium at a temperature ofabout 930° C. with an average strain rate of 10⁻³s⁻¹. The dimensions ofthe titanium material blank were 230 mm by 435 mm. An isothermalhydraulic press having 1600 ton capacity was used for forging. The presscomprised an isothermal die block, which was manufactured from a heatresistant nickel alloy that was heated up to a similar temperature asthe titanium material blank. The deformation corresponded to forgingwith similar deformation axes. After two repeated deformation steps asdecribed above, a highly homoheneous titanium material microstructurehaving a grain size in a range from about 4 μm to about 8 μm was formed.Strain during forging was about 50% in relation to the titanium materialblank height dimension. Sum relative strain, measured by a change of thetitanium material blank area on each stage, was about 12.

The titanium material blank was in superplasticity ranges during thetitanium material production method, as a grain size in a range fromabout 4 μm to about 8 μm, a deformation temperature of about 930° C.,strain rate ε equal to about 10⁻³ s⁻¹, and a sensitivity ratecoefficient m of about 0.49. The titanium material blanks were subjectedto annealing at the deformation temperature for about 1 hour forrecrystallization. The final dimensions of the blank were about 250 mmby about 300 mm.

EXAMPLE 3

Titanium material blanks comprising a two-phase titanium alloy (VT8-1)were provided, in which the titanium material blanks possessed a Tpt ofabout 965° C. as an ingot and a Tpt of about 1000° C. as a forging. Theingot, which has a size of about 628 mm by 535 mm, was subjected to aforging in the β-region of titanium. The forging was followed by heattreatment at about 1200° C., and forging that included rollforming,settling, forging on a square, and rollforming. This step was followedby heat treatment at about 1140° C., forging to about 390 mm, and acooling by air. Further, a heat treatment at about Tpt−30° C. andforging to 310 mm, heating at about 1060° C. and forging to 280 mmfollowed by cooling in air were also conducted on the titanium materialblanks.

The titanium material blank can then be subjected to heating at aboutTpt−30° C. followed by forging. The forging included settling, forgingon a square, roll-forming, and forging to 245 mm. After a heat treatmentin the β-region (Tpt+20° C.), a homogeneous titanium materialmicrostructure with a grain size in a range from about 810 μm to about850 μm was formed. Cooling of the titanium material blanks was conductedby water quenching.

Forging in the (α+β)-region for titanium material was conducted at atemperature of about 930° C. and an average strain rate 10⁻³s⁻¹. Thedimensions of the titanium material blank were 230 mm by 435 mm. Anisothermal hydraulic press with the 1600 ton capacity was used forforging. The press comprised an isothermal die block, which wasmanufactured from a heat resistant nickel alloy. The die block washeated up to the same temperature as the titanium material blank. Thedeformation corresponded to a forging deformation axis. After twodeformation steps were conducted, a highly homoheneous titanium materialmicrostructure with the fine grain size in a range from about 5 μm toabout 8 μm was formed. Strain during forging was 50% in relation to thetitanium material blank height dimension. Sum relative strain, measuredby a change in titanium material blank area, was 12.

The titanium material was in superplasticity regions during the titaniummaterial production method, because of the grain size in a range fromabout 4 μm to about 8 μm, a deformation temperature of about 930° C., astrain rate ε equal to about 10⁻³s⁻¹, and rate sensitivity coefficient mof about 0.49. The titanium material blanks were subjected to annealingat the deformation temperature for about 1 hour for recrystallization.The final dimensions of the blank were about 250 mm by 300 mm.

EXAMPLE 4

Titanium material blanks comprising a two-phase titanium alloy VT6 wereused, in which the titanium material blanks had a Tpt of about 990° C.in an ingot and Tpt of about 990° C. in a forging. The titanium materialingot has a size of about 736 mm by 1523 mm and was subjected to forgingin the β-region. The forging included heating to 1200° C., extention to620 mm, and heating to 1200° C. and extention to 510 mm. The titaniummaterial blank was then cut in 2 pieces, and subjected to further heattreatment. The heat treatment included heating to 1100° C., extention to410 mm, and cooling by air. Further, the titanium material productionmethod included heating at a temperature (Tpt−40° C.), extention to 370mm, heating at 950° C., and forging to 320 mm were conducted. Further,the titanium material production method included heating to 1060° C.,extention to 295 mm and water cooling, and cutting into two pieces.Further, the titanium material blank was heated to Tpt−30° C., deformingto a height of about 390 mm, heating to 960° C., deforming to a height350 mm, forging to a square 280 mm, roll forming to 320 mm wereconducted. Further, a repeat of these steps operations were conductedand final titanium material blank had size of about 245 mm.

Forging in the (α+β)-region was conducted at about T equal to about 940°C. and the average strain rate 10⁻³s⁻¹. The dimensions of the blank were230 mm by 435 mm. Isothermal hydraulic press with a 1600 ton capacitywas used. The press comprised the isothermal die block that wasmanufactured from heat resistant nickel alloy and was heated to thetemperature of the titanium material blank. The deformation correspondedto deformation axes. After two steps of deformation were conducted, ahighly titanium material homoheneous microstructure with a fine grainsize in a range from about 6 μm to about 10 μm was formed. The strainduring forging was about 50% with respect to titanium material blankdimensions. Sum relative strain measured by a change of the titaniummaterial blank was about 12.

It was determined from the grain size in a range from about 6 μm toabout 10 μm, a deformation temperature at about 930° C., strain rate εequal to about 10⁻³s⁻¹, and a rate sensitivity coefficient m equal toabout 0.35 that superplasticity conditions were provided in the titaniummaterial production method, as embodied by the invention. To reachrecrystallization, the titanium material blanks were subjected toannealing at the deformation temperature for about 1 hour. The finaldimensions of the titanium material blank were 250 mm by 300 mm.

EXAMPLE 5

Titanium material blanks comprising a two-phase titanium alloy (VT6) wasused, in which the titanium material had a Tpt of about 990° C. in aningot form and a Tpt of about 990° C. as a forging. Ingot dimensionswere 736 by 2500 mm. Titanium material blanks were cut with dimensions180 by 220 mm. The sizes of the titanium material grain in a longtitudaldirection were in a range from about 50 mm to about 70 mm, and in thelateral direction were in a range from about 15 mm to about 20 mm.

The titanium material blank was subjected to forging, which includedheating at 1100° C., settling, deformation to 130 mm, heating at 1050°C., settling, deformation to 130 mm, and cooling by water. Further, thetitanium material production method included heating at Tpt−40° C.,settling, and deformation to 130 mm. Further, heating at 1020° C.,deformation to 130 mm and water cooling were included in the titaniummaterial production method, as embodied by the invention.

The titanium material production method included forging in the(α+β)-region and with average strain rate 2×10⁻²s⁻¹. The dimensions ofthe blank were 230 mm by 435 mm. Isothermal hydraulic press with a 1600ton capacity was used. The press comprised the isothermal die block thatwas manufactured from heat resistant nickel alloy and was heated to thetemperature of the titanium material blank, for example a temperature ina range from about 400° C. to about 450° C. At T equal to about 980° C.,the titanium material blank was subjected to the settling of 50%.Further, at the temperatures of 850° C. and 950° C., the furthersettling was conducted followed by quenching. After three deformationsteps were conducted with annealing at 900° C., the highly homoheneousmicrostructure with the grain size in a range from about 2 μm to about 5μm was formed. Sum relative strain measured by a change of titaniummaterial blank area was 16. The final dimensions of the titaniummaterial blank were 110 mm by 300 mm.

The titanium material production methods, as embodied by the inventionincluding those discussed above, can provide titanium articles andstructures with suitable homogeneous fine-grain microstructures. Theproduced titanium material is intended to be suitable for variousapplications, such as, but not limited to, turbine componentapplications. Further, the produced titanium material possesseshomogeneous fine-grain microstructures that can be readily evaluated byultrasonic inspection methods and systems.

A general discussion of ultrasonic inspection will now be provided withreference to titanium materials, which can be produced by titaniummaterial production methods, including titanium material productionmethods, as embodied by the invention. The following discussion willrefer to titanium articles and structures, which include titaniummaterials that are prodiced by titanium material production methods, asembodied by the invention.

The titanium material produced by titanium material production methods,as embodied by the invention, can be inspected to determine if thetitanium material microstructures comprise fine-scale granular αTiparticles. Also, the titanium material can be used to form titaniummaterial articles and structures that can be evaluated by ultrasonicinspection to result in enhanced determinations and indications ofuniform-fine grain (UFG) billets and forgings made from UFG billets.Further, the produced titanium material can provide titanium materialarticles and structures, in which the titanium articles and structuresgenerally generate predominantly Rayleigh scattering during ultrasonicinspection, which is indicative of uniform-fine grain microstructure inthe titanium material. The functionality of scattering as a function ofacoustic entity size and ultrasound wavelength varies in a smoothfashion from one regime (“Rayleigh” to “phase” to “diffusion”) toanother. For adequate inspection to find critical flaws, and to assurepredominantly Rayleigh scattering, the acoustic entity size needs to benot greater than about {fraction (1/10)} the wavelength of the soundused for inspection. The generated Rayleigh scattering from titaniumarticles and structures, as embodied by the invention, is typicallyindicative that the titanium articles and structures compriseuniform-fine grains (UFG). Thus, the produced titanium materials, asembodied by the invention, are suitable for various microstructurallysensitive applications, such as but not limited to turbine components.

Therefore, the titanium material that is produced by titanium materialproduction methods, as embodied by the invention, can be inspected byultrasonic inspection with enhanced results, because UFG titaniummicrostructures generate predominantly Rayleigh scattering. If theultrasonic inspection determines scattering other than predominantlyRayleigh scattering, for example phase scattering alone or incombination with Rayleigh scattering, it is possible to characterize thetitanium articles and structures as not comprising uniform-fine graintitanium.

αTi particles are generally less than about 5 μm in diameter, and aregenerally formed with an absence of crystallographic texture. Theultrasonic inspectability of these UFG titanium materials ischaracterized by a signal to noise ratio from machined flat bottomholes. The signal to noise ratio obtained by ultrasonic inspection isgreater in UFG titanium materials than in the conventional titaniummaterials. It has been determined that there is less ultrasonicbackscattered noise in the UFG titanium materials than in theconventional titanium materials. Further, it has been determined usingultrasonic inspection of titanium articles and structures that anultrasonic signal from machined flat-bottomed holes is higher in the UFGtitanium material.

Further, the ultrasonic inspection of titanium articles and structuresindicates that the presence of a αTi particle colony structure isassociated with ultrasonic noise. For titanium materials with αTiparticles less than about 10 μm in size, differences in αTi particlesize typically do not have a significant effect on generated ultrasonicnoise. For example, UFG billets display chiefly Rayleigh scattering,while conventional billets, which are not be characterized by UFGproperties, display Rayleigh scattering plus phase scattering whensubjected to ultrasonic inspection. Therefore, the inspectability oftitanium-containing materials is enhanced using titanium articles andstructures that generate predominantly Rayleigh scattering.

The titanium articles and structures for ultrasonic inspection compriseUFG microstructural characteristics and features that can be determinedusing the titanium article's sound scattering sensitivity. Theultrasonic inspection method comprises providing a titanium articles andstructures, for example a Ti6242 alloy. This Ti6242 alloy material ismerely exemplary of the titanium materials for titanium articles andstructures within the scope of the invention. The description of aTi6242 alloy for the titanium articles and structures is in no wayintended to limit the scope of the invention.

The titanium articles and structures (or “titanium material”) issubjected to ultrasonic inspection by directing ultrasonic energy ontothe titanium material. The ultrasonic energy directed into the materialtypically comprises a pulse of sound at a selected frequency. The soundpulse is scattered in a manner determined by the frequency of the soundpulse, the microstructural features of the titanium material, and byintrinsic physical characteristics, such as but not limited to, elasticconstants and mass density, of the titanium material. The scatteredenergy is then analyzed and a determination of the characteristics ofthe scattered noise is made with regard to the nature of the scatteringfor the titanium articles and structures.

The titanium material for ultrasonic inspection comprises a uniform finegrain (UFG) material, which can be produced by forging a billet ofconventional titanium material into various and appropriate structures,configurations, and shapes. For example, the UFG titanium articles andstructures can be formed by steps of press forging, heat-treating,quenching, and subsequent cooling. The titanium that is actuallysubjected to the ultrasonic inspection may be further prepared byproviding a titanium billet with at least one, for example a series, offlat bottom holes. These flat bottom holes will serve as pixel intensitystandards, upon which the ultrasonic inspection can be gauged.

A signal to noise ratio for synthetic flaws machined in the Ti6242blocks is strongly influenced by titanium microstructural condition, forexample as the Ti6242 is defined by electron backscatter diffractionanalysis. Ti6242 blocks having a microstructure comprising uniform,fine, texture-free αTi particles typically provided signal to noiseratios about 20 dB greater than similar titanium blocks withmicrostructures having colonies comprising crystallographically alignedαTi particles.

The ultrasonic inspection method and procedure will now be describedwith reference to titanium articles and structures and titaniummaterials, which are produced by titanium material production methods,as embodied by the invention. In the following discussion, the terms areused with their normal meanings as understood by person of ordinaryskill in the art, unless discussed to the contrary. Further, thedimensions are approximate, unless stated to be exact.

The ultrasonic inspection provides titanium articles and structures,such as a Ti6242 alloy, for evaluation. The Ti6242 material is evaluatedwhen the titanium material has been configured into four microstructuralconditions: a conventional billet; a conventional forging fromconventional billet; a uniform fine grain (UFG) billet; and a forging ofthe UFG billet. The individual billets will be referred to by the abovenames, and collectively as “billets”.

The conventional billet is about 23 centimeters (cm) (9 inch) indiameter. The conventional forging is from the bore region of a diskforging, for example a compressor disk forging. The UFG billet isproduced as two bars from about 10 cm×10 cm×20 cm sections taken fromthe commercial billet and having its grain refined under acceptedtitanium alloy grain refinement processes. The forging of UFG billet isproduced by press forging at temperatures of about 900° C. about a 7 cmtall, 6.35 cm diameter cylinder of the UFG billet to about a 2.80 cmfinal height at 2.5 cm/min pressing speed. The forging of UFG billet isgiven a heat treatment of about 970° C., for about 1 hour, followed by ahelium quench, at about 705° C., for about 8 hours, followed by an aircool.

The microstructure of each billet is then evaluated by light microscopy.The crystallographic texture of each billet is then determined byelectron backscatter diffraction pattern (EBSP) analysis. Lightmicrographs for each billet are displayed in FIG. 1, where legend (a) isthe conventional billet; legend (b) is the conventional forging; legend(c) is the UFG billet; and legend (d) is the forged UFG billet. FIG. 2shows EBSP “icosahedral” images, in which the [0001] pole inclination ofa scanned microstructure is represented in colors. In FIG. 2, colorsthat are close to one another on an accepted “20-sided (icosahedral)color sphere” represent microstructure inclinations that are similar inpole inclination. Further, in FIG. 2, a black pixel is a pixel for whichno crystallographic orientation can be determined. Further, FIG. 3 shows[0001] pole figures for the regions of the scanned images FIG. 2. Thelegends for FIGS. 2 and 3 are similar to those of FIG. 1.

As illustrated, the conventional billet microstructure contains primaryαTi particles, with a thickness of about 5 μm, and lengths in a rangefrom about Sum to about 10 μm, as illustrated in FIG. 1, legend (a). TheαTi particles are arranged in colonies, typically about 100 μm wide andover about 300 μm long, as illustrated in FIG. 2, legend (a). The αTiphase orientation of the sample scanned in FIG. 2, legend (a) indicatestrong crystallographic texture, with most [0001] poles in the lowerregion of the pole, as illustrated in FIG. 3, legend (a).

The microstructure of the forging from the conventional billet containsprimary αTi particles, with diameters in a range from about 5 to about10 μm, FIG. 1, legend (b). As illustrated, there appears to besubstantial breakup of the billet microstructure. αTi particles arearranged in large colonies comprising similar crystallographicorientations. For example, some αTi colonies are about 300 μm wide andoften greater than about 1000 μm long, as illustrated in FIG. 2, legend(b). The αTi phase orientation of the sample scanned in FIG. 2, legend(b) has strong crystallographic texture, meaning that a majority of the[0001] poles are grouped within two regions of the pole figure, asillustrated in FIG. 3, legend (b). This strong grouping of the polessuggests that the scanned region comprises two colonies.

The ultrasonic inspection of the UFG billet indicates a microstructurecomprising αTi particles. The particles comprise diameters about 5 μm,as illustrated in FIG. 1, legend (c). These αTi particles do not appearto be provided in colonies, as illustrated in FIG. 2, legend (c). TheαTi phase orientation of the sample scanned as illustrated in FIG. 2,legend (c) appears random, as illustrated in FIG. 3, legend (c).

The microstructure of the heat-treated forging of the UFG billetindicates that it comprises αTi particles. The αTi particles havediameters about 10 μm, as illustrated in FIG. 1, legend (d). These αTiparticles are larger than the billet from which the αTi particles areformed, and this suggests grain growth during at least one of forging orheat treatment of the UFG billet. The αTi particles are not provided incolonies, as illustrated in FIG. 2, legend (d). The αTi phaseorientation appears random, as illustrated in FIG. 3, legend (d).

The ultrasonic characteristics of the billets formed different titaniumarticles and structures are determined by C-scans of blocks formed frombillets of the titanium articles and structures. The titanium articlesand structures are provided as blocks about 0.79 mm ({fraction (1/32)}inch) diameter flat bottom holes. The titanium blocks are formed about38 mm thick with holes drilled to about 25 mm below top surface of theblock. Each of the conventional billet, conventional forging, and UFGbillet have surface dimensions about 64 millimeters (mm) square, andeach also has 9 flat bottom holes. The forging made from the UFGmaterial had dimensions about 64 mm by about 28 mm, and is provided with6 flat bottom holes. Each titanium block is machined with sufficientorientations so that an ultrasonic inspection direction is similar tothat of a larger component formed from the titanium articles andstructures. For example, the 38 mm thickness of the titanium block isdisposed in the radial direction of the billet or forging.

The ultrasonic transducers used for the ultrasonic inspection byC-scanning processes are listed in Table 1. Table 1 also providescharacteristics of the ultrasonic transducers. The transducers comprisepolyvinylidine fluoride (PVDF) as a piezoelectric element. Centerfrequencies for the ultrasonic transducers are measured from signalsreflected off the backwall of a fused silica block. TABLE 1Characteristics of Transducers Nominal Actual Focal Transducer FrequencyFrequency Diameter Length Aperture 1  5 MHz  6.62 MHz 19 mm 133 mm f/7 210 MHz 11.36 MHz 19 mm 133 mm f/7 3 20 MHz 18.43 MHz 19 mm 133 mm f/7

Two separate series of water immersion ultrasonic C-scans were performedon the titanium-containing blocks. The series of water immersionultrasonic C-scans were performed at nominal frequencies of about 5 MHz,about 10 MHz, and 20 MHz. One scan at each of the above-frequencies isperformed to measure a signal from the flat bottom holes. A second scanat each of the above-frequencies is performed at a higher amplificationto get noise and sound scattering sensitivity statistics.

Each of the scans is made over a square region about 147.5 mm in lengthand width, with about a 0.144 mm scan and index increment. The sound isfocused about 25 mm below the top surface of the blocks, which isdisposed in the approximate the plane of the flat bottom holes. Thewidth of scan signal gate is about 4 microseconds. The obtained C-scanimages are about 1024 pixels by about 1024 pixels.

FIG. 4, legends (a)-(d), illustrate C-scan images made at about 5 MHz.With reference to FIG. 4, the UFG billet material is in the upper left,the conventional billet is on the upper right, the conventional forgingis on the lower left, and the forging of the UFG material is on thelower right. The conventional billet and forging exhibit a higherbackground noise, as indicated by brighter pixels in those blocks asillustrated in FIG. 4, legend (a). A lower intensity is exhibited fromthe flat bottom holes, as indicated by a lower intensity of pixels fromthose regions as illustrated in FIG. 4, legend (b).

Quantitative measures of signal and noise can then be determined fromthe C-scans. The signal from each flat bottom hole is taken as thebrightest pixel within the 3×3 array of the nine brightest pixels. Noisestatistics and sound scattering sensitivity can then be determined fromsquare pixel arrays that did not comprise the flat bottom holes. Thequantitative data is presented in Table 2. In Table 2, a signal is anaverage signal from all flat bottom holes in the respective block. Thesignal to noise ratios are calculated both as:(Average Signal−Average Noise)÷(Maximum Noise−Average Noise)as well as:(Average Signal−Average Noise)÷(3σ_(Noise)). TABLE 2 Ultrasonic Signalsand Noise Measurements in Ti6242 Blocks FBH Signals Attenu- Attenu-ation ation Noise Material MHz DB S dB N_(ave) N_(Max) σ_(noise)Conventional 6.62 −34 94.4 −12 61.3 141 11.1 billet Conventional, 6.62−34 53.4 −12 44.7 107.5 9.48 forged UFG billet 6.62 −34 216.1 −12 9.134.5 1.70 UFG, forged 6.62 −34 108.5 −12 4.3 12.5 0.973 Conventional11.36 −49 75.4 −12.5 130.9 243.5 21.5 billet Conventional, 11.36 −4942.7 −12.5 81.8 249.5 17.2 forged UFG billet 11.36 −49 214.5 −12.5 23.159.5 4.38 UFG, forged 11.36 −49 100.5 −12.5 5.9 11.5 1.11 Conventional18.43 −48.5 51.3 −10 73.6 168.5 12.4 billet Conventional, 18.43 −48.520.4 −10 38.8 142.5 8.35 forged UFG billet 18.43 −48.5 212.2 −10 21.571.5 4.11 UFG, forged 18.43 −48.5 93.5 −10 11.9 20.5 1.40

The determined signal to noise ratio calculations for titanium materialsare listed in Table 3. Both calculation methods, as described above,provide a measure of a signal's intensity in a selected block relativeto noise spikes in the same block. TABLE 3 Signal to Noise Ratio inTi6242 Blocks Signal to Noise Ratio (S_(ave) − N_(ave))/ (S_(ave) −N_(ave))/ Material MHz (N_(Max) − N_(ave)) 3σ_(noise) Conventionalbillet 6.62 14.2 33.9 Conventional, 6.62 10.0 22.0 forged UFG billet6.62 106.7 531.3 UFG, forged 6.62 166.6 466.4 Conventional billet 11.3643.6 76.1 Conventional, 11.36 16.5 53.7 forged UFG billet 11.36 393.71089.8 UFG, forged 11.36 1195.2 2015.7 Conventional billet 18.43 44.7113.8 Conventional, 18.43 16.2 67.0 forged UFG billet 18.43 356.7 1445.5UFG, forged 18.43 915.0 1873.2

Accordingly, if the determining a signal to noise ratio level isconducted by (Average Signal−Average Noise)÷(Maximum Noise−AverageNoise), it can be generalized that the material comprises uniform finegrains at 6.62 MHz if the a signal to noise ratio—for a signal from 0.79mm ({fraction (1/32)} inch) diameter flat bottom holes 25 mm below theinspected surface of the material—is at least about 20; at 11.36 MHz asignal to noise ratio level is at least about 50; and at 18.43 MHz asignal to noise ratio level is at least about 50. Further, if thedetermining a signal to noise ratio level is conducted by (AverageSignal−Average Noise)÷(3σ_(Noise)) for the subject flat bottom holes, itcan be also generalized that the material comprises uniform fine grainsat 6.62 MHz if the a signal to noise ratio level is at least about 50;at 11.36 MHz a signal to noise ratio level is at least about 100; and at18.43 MHz a signal to noise ratio level is at least about 150. Each ofthese signal to noise ratio levels correspond to a preset noise level asdetermined by the pre-drilled holes in the material.

The highest signal from flat bottom holes is measured in the UFG billet,and the lowest signal from flat bottom holes is measured in aconventional forging, as illustrated in the graph of FIG. 6. The highestaverage noise, the largest maximum noise, and the largest standarddeviation of noise are measured in a conventional billet. The lowestaverage noise, the smallest maximum noise, and the smallest standarddeviation of noise are measured in forging of UFG material, asillustrated in the graph of FIG. 7. Accordingly, it can be determinedthat the forged UFG material possesses the highest signal to noiseratio, and that the conventional forging had the lowest signal to noiseratio, as illustrated in the graph of FIG. 8.

In the ultrasonic inspection of the titanium articles and structures,longitudinal sound velocities were measured in a Ti6242 extrusion. TheTi6242 extrusion was processed to create a strong [0001] texture in thedirection of extrusion. For example, the extrusion of the Ti6242 isperformed at about 1040° C. and a ratio of about 8:1. The extrusion isthen heat treated at about 593° C. for about 8 hours. X-rayinvestigation and analysis determine the grain and microstructureorientation of the Ti6242. This investigation and analysis of the Ti6242indicates a strong [0001] texture along the extrusion direction, with[0001] intensity along the extrusion direction. The intensity has beendetermined to be about 22 times random.

The ultrasonic behavior of small titanium articles and structures, forexample a Ti6242 alloy, can be determined by ultrasonic inspection ofthe titanium articles and structures as a function of ultrasonicfrequency and material microstructure. The speed of sound in αTi isabout 6 mm/μs. At an ultrasonic frequency of 5 MHz, the wavelength isabout 1.2 mm in the titanium articles and structures. Colony sizesgreater than about 200 μm could change the scattering character fromRayleigh toward stochastic (phase). Sound velocities in the Ti6242 aremeasured on rectangular Ti6242 pieces that are formed from therespective Ti6242 billets. The rectangular Ti6242 pieces are about 16 mmlong in the extrusion direction and about 12 mm in length in a directionnormal to the extrusion direction. Longitudinal velocity is measured atabout 10 MHz with a contact transducer, amplifier, and oscilloscope. Thelongitudinal velocity is determined by measuring a time for a soundpulse to travel down the selected direction and return. The soundvelocity along the extrusion direction is about 6.28 mm/μs; while thesound velocity in a direction normal to the extrusion direction is about6.1 mm/μs.

The results from the ultrasonic inspection and the determination of thetitanium articles and structures, along with microstructurecharacteristic of the titanium articles and structures are based on UFGbillet blocks, which are formed from conventional billet material, asdescribed above. The UFG process produces samples in which the originalαTi colony structure in the conventional billet is eliminated. The stepsof forging the UFG material at about 900° C. and with a correspondingabout a 60% height reduction did not re-create αTi colonies or developstrong texture and αTi microstructure.

With reference to FIGS. 6 and 7, differences in sound scatteringsensitivity and noise are illustrated to be generally dependent onfrequency. This dependency suggests that a scattering entity size, suchas the size of a colony, in the conventional material increases thecontribution to scattering, sound scattering sensitivity, andattenuation from phase scattering. This change in contribution is not acomplete shift from one pure scattering mechanism to the otherscattering mechanism, such as a Rayleigh scattering mechanism to a phasescattering mechanism, since such a shift would give a slope of about −2in FIG. 5.

The αTi particle size is generally not significant in any determining ofa signal to noise ratio, since the αTi particle sizes are similar in allmaterials and are generally smaller in size than the ultrasonicwavelength. A difference in the various materials, in the ultrasonicinspection comprises a presence of large colonies in conventionalbillets and forgings. Noting this difference, the speed of sound inTi6242 extrusion samples is about 6 mm/μs. This speed typicallycorresponds to ultrasonic inspection wavelengths of about 1.2 mm atabout 5 MHz, about 600 μm at about 10 MHz, and about 300 μm at about 20MHz. Therefore, the colony dimensions in the conventional billet andforging are comparable to the ultrasonic wavelength.

The relative contributions of Rayleigh scattering and phase scatteringare frequency dependent, for example in the ultrasonic frequency range.The frequency dependency is due, at least in part, to the 18.43 MHzwavelength of about 300 μm being about the size of a αTi colonythickness. The 6.62 MHz wavelength of about 900 μm is about 3 times aαTi colony size. Scattering at 6.62 MHz enters the phase scatteringregion for its contribution, while scattering at 18.43 MHz providessubstantial phase scattering contributions.

The UFG forged material results in a slightly larger grain size than theoriginal billet. However, UFG forged material possesses a lower noiseand higher signal, as indicated in Table 2. This behavior may be due toa slightly lower volume fraction of αTi particles in the forgedmaterial, which is illustrated in FIG. 1, legends (c) and (d).

The conventional forging possesses a lower noise than a conventionalbillet, however, has a lower signal to noise ratio, which may be due inpart to low signals from the flat bottom holes. The conventional forginghas a lower volume fraction of αTi particles than the billet. The lowersignal in the conventional forging may be caused by attenuation due, atleast in part, to sound traveling along highly textured regions. Thedimensions of the reflecting entity αTi colonies up to about 1 mm inlength and about 300 μm in width in the conventional billet and forgingmay result in a stochastic (phase) component to the resultantscattering. It is also possible that a αTi colony structure above theflat bottom holes scatters the reflection from the flat bottom holes.

The microstructures of UFG billets and forgings made from UFG billetscomprise fine-scale granular αTi particles. These αTi particles aregenerally less than about 5 μm in diameter, and are generally providedwith an absence of crystallographic texture. Ultrasonic inspectability,which is characterized by signal to noise ratio from machined flatbottom holes, is greater in the UFG materials than in the conventionalmaterials. There is less ultrasonic backscattered noise in the UFGmaterials than there is in the conventional materials. Further, theultrasonic signal from machined flat bottomed holes is higher in the UFGmaterial.

The presence of αTi colony structure is associated with ultrasonic noisegenerated by ultrasonic inspection of titanium articles and structures,as embodied by the invention. For materials with αTi particles less thanabout 10 μm in size, differences in αTi particle size typically do nothave a significant effect on generated ultrasonic noise. For example,UFG billets, which may be formed by a titanium material productionmethod, as embodied by the invention, can display chiefly Rayleighscattering, while conventional billets, which can not be characterizedby UFG properties, display Rayleigh scattering plus phase scattering.The inspectability of titanium-containing materials is enhanced withpredominantly Rayleigh scattering.

While various embodiments are described herein, it will be appreciatedfrom the specification that various combinations of elements, variationsor improvements therein may be made by those skilled in the art, and arewithin the scope of the invention.

1. A titanium material production method for producing homogeneous finegrain titanium material in which the titanium material has a grain sizein a range from about 5 μm to about 20 μm, the method comprising thesteps of: providing a titanium material blank; conducting a first heattreatment on the titanium material blank to heat the titanium materialblank to a β-range; quenching the titanium material blank from theβ-region to the α+β-region; forging the titanium material blank; andconducting a second heat treatment; wherein the titanium materialproduction method subjects the titanium material blank tosuperplasticity conditions during the titanium material productionmethod.
 2. A titanium material production method according to claim 1,the titanium material production method comprising heating the titaniummaterial blank to a temperature in a range from about 600° C. to aboutTpt, wherein Tpt is a polymorphous transformation temperature for thetitanium material.
 3. A titanium material production method according toclaim 1, the step of providing a titanium material blank comprisesproviding a titanium material blank formed by powder metallurgyprocesses.
 4. A titanium material production method according to claim1, wherein the titanium material production method produces titaniummaterial comprising generally equiaxed titanium grains and generallyequally sized titanium grains.
 5. A titanium material production methodaccording to claim 1, wherein the titanium material production methodproduces titanium material comprising
 6. A titanium material productionmethod according to claim 1, wherein the step of providing a providing atitanium material blank comprises providing a two-phase titaniummaterial blank.
 7. A titanium material production method according toclaim 1, wherein the step of conducting a first heat treatment on thetitanium material blank to heat the titanium material blank to a β-rangecomprises heating at about 1200° C. for about 1 hour.
 8. A titaniummaterial production method according to claim 1, wherein the titaniummaterial production method comprises heating the titanium material blankto a temperature in a range from about 875° C. to about 1200° C.
 9. Atitanium material production method according to claim 1, wherein thestep of forging comprises deforming the titanium material blank in aisothermal press.
 10. A titanium material production method according toclaim 9, wherein the step of deforming comprises multiple steps ofdeforming.
 11. A titanium material production method according to claim1, wherein the titanium material production method produces titaniummaterial with a grain size in a range from about 15 μm to about 20 μm.12. A titanium material production method according to claim 1, whereinthe step of forging comprises at least one of: roll-forming, deformationin a press, and forging in a square.
 13. A titanium material productionmethod according to claim 11, wherein the step of forging comprisesmultiple steps of deforming.
 14. A titanium material production methodfor producing homogeneous fine grain titanium material in which thetitanium material has a grain size in a range from about 15 μm to about20 μm, generally equiaxed titanium grains and generally equally sizedtitanium grains, and substantially even distribution of second phaseparticles and alloying elements; the method comprising the steps of:providing a titanium material blank, the titanium material comprising atwo-phase titanium material; conducting a first heat treatment on thetitanium material blank to heat the titanium material blank to aβ-range; quenching the titanium material blank from the β-region to theα+β-region; forging the titanium material blank; and conducting a secondheat treatment on the titanium material blank, wherein the titaniummaterial production method subjects the titanium material blank tosuperplasticity conditions during part of the titanium materialproduction method, the titanium material production method comprisingheating the titanium material blank to a temperature in a range fromabout 600° C. to about Tpt, wherein Tpt is a polymorphous transformationtemperature for the titanium material.